Leydig cell (LCs) apoptosis is responsible for decreased serum testosterone levels during late-onset hypogonadism (LOH). Our study was designed to illustrate the regulatory effect of lncRNA XIST on LCs and to clarify its molecular mechanism of action in LOH. The Leydig cells (TM3) was treated by 300 μM H₂O₂ for 8 h to establish Leydig cell oxidative stress model in vitro. The expression levels of lncRNA XIST in the testicular tissues of patients with LOH were measured using fluorescence in situ hybridization (FISH). The interaction between lncRNA XIST/SIRT1 and miR-145a-5p was assessed using starBase and dual-luciferase reporter gene assays. Apoptotic cells and Caspase3 activity were determined by flow cytometry (FCM) assay. Testosterone concentration was determined by ELISA. Moreover, histological assessment of testicles in mice was performed by using HE staining and the TUNEL assay was used to determine apoptosis. We found that the lncRNA XIST was downregulated in the testicular tissues of LOH patients and mice and in H₂O₂-induced TM3 cells. XIST siRNA significantly promoted apoptosis, enhanced Caspase3 activity and reduced testosterone levels in H₂O₂-stimulated TM3 cells. Further studies showed that the miR-145a-5p inhibitor reversed the effect of XIST-siRNA on H₂O₂-induced Leydig cell apoptosis. MiR-145a-5p negatively regulated SIRT1 expression, and SIRT1-siRNA reversed the effects of the miR-145a-5p inhibitor on H₂O₂ stimulated TM3 cells. The in vivo experiments indicated that silencing of the lncRNA XIST aggravated LOH symptoms in mice. Inhibition of lncRNA XIST induces Leydig cell apoptosis through the miR-145a-5p/SIRT1 axis in the progression of LOH.

间质细胞 (LC) 凋亡是迟发性性腺功能减退症 (LOH) 期间血清睾酮水平降低的原因。我们的研究旨在阐明 lncRNA XIST 对 LC 的调节作用，并阐明其在 LOH 中的分子作用机制。 300 μM H ₂ O ₂处理Leydig细胞（TM3）8 h，建立Leydig细胞体外氧化应激模型。使用荧光原位杂交（FISH）测量 LOH 患者睾丸组织中 lncRNA XIST 的表达水平。使用 starBase 和双荧光素酶报告基因测定评估 lncRNA XIST/SIRT1 和 miR-145a-5p 之间的相互作用。通过流式细胞术 (FCM) 测定测定凋亡细胞和 Caspase3 活性。睾酮浓度通过ELISA测定。此外，使用HE染色对小鼠睾丸进行组织学评估，并使用TUNEL法测定细胞凋亡。我们发现lncRNA XIST在LOH患者和小鼠的睾丸组织以及H ₂ O ₂诱导的TM3细胞中下调。 XIST siRNA 显着促进 H ₂ O ₂刺激的 TM3 细胞凋亡、增强 Caspase3 活性并降低睾酮水平。进一步的研究表明，miR-145a-5p抑制剂逆转了XIST-siRNA对H ₂ O ₂诱导的Leydig细胞凋亡的影响。 miR-145a-5p负向调节SIRT1表达，SIRT1-siRNA逆转miR-145a-5p抑制剂对H ₂ O ₂刺激的TM3细胞的影响。体内实验表明，lncRNA XIST 的沉默会加重小鼠的 LOH 症状。在 LOH 进展过程中，抑制 lncRNA XIST 可通过 miR-145a-5p/SIRT1 轴诱导 Leydig 细胞凋亡。